Integrated Circuit with Shared Electrode Energy Storage Devices

ABSTRACT

An integrated circuit has a substrate, a super-capacitor supported by the substrate, and a battery supported by the substrate. The super-capacitor includes a super-capacitor electrode and a shared electrode, and the battery has a battery electrode and the prior noted shared electrode. The super-capacitor and battery form at least a part of a monolithic integrated circuit.

REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is related to the following patent application,each of which is incorporated herein, in its entirety, by reference:

-   -   U.S. patent application Ser. No. 14/469,004, filed Aug. 26,        2014, entitled, “METHOD OF PRODUCING A SUPER-CAPACITOR,”        assigned attorney docket number 2550/E73, and naming Yingqi        Jiang and Kuang L. Yang as inventors,    -   U.S. patent application Ser. No. 14/492,376, filed Sep. 22,        2014, entitled, “SUPER-CAPACITOR WITH SEPARATOR AND METHOD OF        PRODUCIGN THE SAME,” assigned attorney docket number 2550/E75,        and naming Yingqi Jiang and Kuang L. Yang as inventors,    -   U.S. patent application Ser. No. 14/509,950, filed Oct. 8, 2014,        entitled, “INTEGRATED SUPER-CAPACITOR,” assigned attorney docket        number 2550/E76, and naming Yingqi Jiang and Kuang L. Yang as        inventors,

FIELD OF THE INVENTION

The invention generally relates to integrated circuits and, moreparticularly, the invention relates to energy storage devices onintegrated circuits.

BACKGROUND OF THE INVENTION

Although the size of portable electronic devices continues to shrink,their energy requirements often do not comparably decrease. For example,a next-generation MEMS accelerometer may have a volume that is 10percent smaller and yet, require are only 5 percent less power than theprior generation MEMS accelerometer. In that case, more of the MEMS diemay be used for energy storage. Undesirably, this trend can limitminiaturization and applicability of such electronic devices.

The art has responded to this problem by developing chip-levelsuper-capacitors (also known as “micro super-capacitors”), which havemuch greater capacitances than conventional capacitors. In a mannersimilar to conventional capacitors, super-capacitors generally havehigher power densities than batteries. Undesirably, however,super-capacitors generally have lower storage capabilities thanbatteries.

SUMMARY OF VARIOUS EMBODIMENTS

In accordance with one embodiment of the invention, an integratedcircuit has a substrate, a super-capacitor supported by the substrate,and a battery supported by the substrate. The super-capacitor includes asuper-capacitor electrode and a shared electrode, and the battery has abattery electrode and the prior noted shared electrode. Thesuper-capacitor and battery form at least a part of a monolithicintegrated circuit.

The battery and super-capacitor may be electrically connected inparallel. Moreover, the shared electrode may be formed at least in partfrom a material so that it has surface energy storage capability (i.e.,an electrode of this type is used for a super-capacitor, such asgraphene) and substantially no volumetric storage capability (i.e., anelectrode of this type is for a battery, such as graphite). The sharedelectrode in that case may form a shared anode for both thesuper-capacitor and the battery. In that case, among other cases, thesuper-capacitor electrode and shared electrode can have about the samecapacitance. As another example, the shared anode embodiment may havethree respective electrodes comprising graphene (super-capacitor),graphene (shared anode), and lithium cobalt oxide (battery cathode).

In contrast, the shared electrode may include a material having bothsurface energy storage capability and volumetric energy storagecapability. In that case, the super-capacitor may form an asymmetricsuper-capacitor with the shared electrode, thus forming a shared cathodefor the super-capacitor and the battery. For example, the shared cathodeembodiment may have three respective electrodes comprising graphene(super-capacitor), and lithium cobalt oxide (shared cathode), and metallithium (battery anode).

In some embodiments, at least one of active circuitry and MEMS structurealso is/are supported by the substrate and in electrical communicationwith the battery and the super-capacitor. For example, the integratedcircuit may include switching circuitry to switch between at least a) afirst state using the battery only, and b) a second state using thesuper-capacitor only. Moreover, the integrated circuit may include aplurality of layers, and at least one of the layers may include two ofthe electrodes. Accordingly, both of these same-layer electrodes may beformed by the same processing/microfabrication step.

The electrodes may be shaped and oriented in a wide variety ofgeometries. For example, the super-capacitor electrode may have aportion that is interdigitated with a portion of the battery electrode.

In accordance with another embodiment of the invention, a micro-levelenergy storage device has a substrate, a first electrode formed from amaterial having surface energy storage capability (but no volumetricenergy storage capability), and a second electrode formed from amaterial having volumetric energy storage capability. The device alsohas a third electrode formed from a material having one or both surfaceenergy storage capability and volumetric energy storage capability, andan electrolyte in communication with the first electrode, the secondelectrode, and the third electrode. The first electrode is configured tointeract with the third electrode to form first energy storage deviceand, in a similar manner, the second electrode is configured to interactwith the third electrode to form a second energy storage device. Thesubstrate, first electrode, second electrode, and third electrode format least a part of a monolithic integrated circuit.

In accordance with other embodiments, a method of forming an integratedcircuit having an energy storage device forms first, second, and thirdelectrodes on a substrate, and adds an electrolyte to the substrate sothat the electrolyte at least partly encapsulates the first and secondelectrodes. The third electrode is spaced from the first and secondelectrodes. The electrolyte is between the first electrode and the thirdelectrode, and between the second electrode and the third electrode. Themethod also separates (e.g., through cutting, dicing, breaking, or otherconventional technique) the substrate into a plurality of individualmonolithic integrated circuit dice/dies. A plurality of the dice havethe first electrode, the second electrode, and the third electrode.Moreover, that plurality of dice each are configured so that the firstelectrode interacts with the third electrode to form first energystorage device, and so that the second electrode interacts with thethird electrode to form a second energy storage device.

BRIEF DESCRIPTION OF THE DRAWINGS

Those skilled in the art should more fully appreciate advantages ofvarious embodiments of the invention from the following “Description ofIllustrative Embodiments,” discussed with reference to the drawingssummarized immediately below.

FIG. 1 schematically shows a perspective view of an integrated circuithaving a shared energy device that may be configured in accordance withillustrative embodiments of the invention.

FIG. 2 schematically shows a cross-sectional view of the integratedcircuit shown in FIG. 1 across line 2-2.

FIG. 3 schematically shows a diagram of the electrical connections of aninternal battery and super-capacitor within the integrated circuit ofFIG. 1.

FIG. 4A schematically shows a first interdigitated arrangement ofelectrodes configured in accordance with illustrative embodiments of theinvention.

FIG. 4B schematically shows a second interdigitated arrangement ofelectrodes configured in accordance with illustrative embodiments of theinvention.

FIG. 4C schematically shows a cross-sectional view of the electrodeimplementations of FIGS. 4A and 4B.

FIG. 5A schematically shows a perspective, exploded view of anotherelectrode arrangement configured in accordance with illustrativeembodiments of the invention.

FIG. 5B schematically shows a cross-sectional view of the electrodearrangement of FIG. 5A.

FIG. 6 shows a process of forming a monolithic integrated circuit havinga shared energy device configured in accordance with illustrativeembodiments of the invention.

FIG. 7A schematically shows a cross-sectional view of the process ofFIG. 6 through step 600.

FIG. 7B schematically shows a cross-sectional view of the process ofFIG. 6 through step 602.

FIG. 7C schematically shows a cross-sectional view of the process ofFIG. 6 through step 604.

FIG. 7D schematically shows a cross-sectional view of the process ofFIG. 6 through step 606.

FIG. 7E schematically shows a cross-sectional view of the process ofFIG. 6 through step 608.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In illustrative embodiments, an integrated circuit has a shared energydevice with a super-capacitor and battery that together share a commonelectrode. Depending on the design, the common electrode can form eithera common anode or a common cathode. Such a shared energy devicetherefore can respond to high-power spikes from an underlying device orcircuit while still delivering effective long-term energy storage needs.Details of illustrative embodiments are discussed below.

FIG. 1 schematically shows a perspective view of an integrated circuit10 having a shared energy device 12 configured in accordance withillustrative embodiments of the invention. FIG. 2 schematically showsone embodiment of a cross-sectional view of the integrated circuit 10along line 2-2 of FIG. 1. As shown, the integrated circuit 10 may beconsidered to be a monolithic, unitary chip-level device having amultilayer substrate 14 supporting a cap 16 that together form aninterior chamber 18. Among other things, the interior chamber 18 has aplurality of electrodes 22A-22C and electrolyte material(s) 24 thattogether form a super-capacitor 26 and a battery 28. In other words, theelectrodes 22A-22C and electrolyte material 24 cooperate to have thecapacity to store a prescribed electrical charge.

The interior chamber 18 also may have internal circuitry 20, which mayinclude any of a wide variety of different devices commonly formed on anintegrated circuit. Among other things, the circuitry 20 can containactive circuit devices (e.g., diodes and transistors) and/or passivecircuit devices (resistors, and inductors, and standard capacitors) thattogether provide the desired functionality. For example, the circuitry20 can form one or more of a digital signal processor, a controller, amicroprocessor, and adder, a digital-to-analog converter, and/or memory.In addition or alternatively, the integrated circuit 10 also may havemovable microstructure and thus, form a microelectromechanical system(i.e., a MEMS device).

In some embodiments, the circuitry 20 may include one or more additionalbatteries and/or super-capacitors that do not share an electrode.Further embodiments may have more shared energy devices 12 similar tothose discussed above and below. Accordingly, illustrative embodimentsare not limited to integrated circuits 10 having one shared energydevice 12 only. For simplicity, FIG. 2 generically identifies both thecircuitry (e.g., additional batteries, super-capacitors, converters,etc.) and microstructure schematically by reference number 20.

The electrode used only for the super-capacitor 26 is referred to hereinas a “super-capacitor electrode 22A” (FIG. 2), while the electrode usedonly for the battery 28 only is referred to herein as a “batteryelectrode 22B” (FIG. 2). The electrode shared by both thesuper-capacitor 26 and the battery 28 simply is referred to herein as a“shared electrode 22C” (FIG. 2). As discussed below, these electrodes22A-22C are formed on the substrate 14, which has an insulation layer33.

In the embodiment shown in FIG. 2, the shared electrode 22C issandwiched between the battery electrode 22B and the super-capacitorelectrode 22A—essentially a “stacked” electrode arrangement. Thus, thebattery electrode 22B and shared electrode 22C interact to form thebattery 28, while the super-capacitor electrode 22A and shared electrode22C interact to form the super-capacitor 26. In some embodiments, theshared electrode 22C and super-capacitor electrode 22A interact to formwhat is known in the art as an “asymmetric super-capacitor.” Asdiscussed in greater detail below, a stacked configuration like thatshown in FIG. 2 is but one of a wide variety of different electrodeconfigurations.

To improve conductivity and provide exterior access to the electrodes22A-22C, illustrative embodiments form current collector layers 30. Eachcurrent collector layer 30 is in electrical contact with one of theelectrodes 22A-22C. In addition, the current collector layers 30 are inelectrical communication with conductive contacts 31 on the exterior ofthe integrated circuit 10. Some embodiments form the conductive contacts31 by elongating the current collector layers 30 to the outside of theinterior chamber 18. Among other things, the current collector layer 30may be formed from a highly conductive metal, such as gold, or a highlydoped semiconductor, such as polysilicon. Those skilled in the art canselect other materials for this purpose.

In preferred embodiments, the battery electrode 22B and thesuper-capacitor electrode 22A are maintained at substantially the samepotential through a connection represented schematically by referencenumber 30A. Although this connection 30A is shown schematically as asimple line, those skilled in the art can use any of a number ofdifferent techniques for making that connection. Some embodiments,however, may not maintain the battery electrode 22B and super-capacitorelectrode 22A at the same potential.

The electrodes 22A and 22B respectively used for the super-capacitor 26and battery 28 may be formed from conventional materials known in theart. More specifically, to improve surface charge storage capacity, thesuper-capacitor electrode 22A preferably is formed from a porousmaterial. For example, the super-capacitor electrode 22A may be formedfrom graphene, which is known to be a porous material with tortuousinterior and exterior surfaces. Virtually every surface of thesuper-capacitor electrode 22A exposed to the electrolyte 24 thereforemay be considered part of the surface area of the capacitor platesrepresented in the well-known equation:

C=ε*(A/D)  (Equation 1),

-   -   where:    -   C is capacitance,    -   ε is a constant,    -   A is the area, and    -   D is distance.

Indeed, those skilled in the art can use other materials to form thesuper-capacitor electrode 22A, such as activated carbon, carbon aerogel,or carbon nanotubes, to name but a few. Some embodiments may from thesuper-capacitor electrode 22A from a plurality of graphene monolayers.Accordingly, discussion of a layer of graphene is by example only andnot intended to limit various other embodiments of the invention.

As known by those skilled in the art, the super-capacitor electrode 22Ahas surface energy storage capability. In particular, this electrode hasthe quality of being capable of storing charge at its surface. Incontrast, however, the super-capacitor electrode 22A does not have theeffective ability to store charge/power an appreciable distance beneathits surface; i.e., at the molecular level within the larger volume ofmaterial forming the super-capacitor electrode 22A.

Super-capacitors therefore typically are considered to have a negligible“volumetric energy storage capacity.” As such, when compared tobatteries, super-capacitors are known to have a lower capability forstoring energy/charge. Despite this shortcoming, super-capacitors alsoare known to have the capability of generally providing higher powerdensities than those of comparably sized batteries. The super-capacitor26 thus should be useful when a circuit powered by the battery 28demands a very high current/power for a short time (a power “spike”). Asdiscussed in more detail below, the shared energy device 12 has thecapability to provide both adequate power during spikes, and substantialenergy storage capability during steady state operation.

The battery electrode 22B may be formed from any conventional materialhaving a non-negligible volumetric energy storage capability. Forexample, among other things, the battery electrode 22B may be formed atleast in part from graphite or lithium. Moreover, although it hassubstantial volumetric energy storage capacity, the battery electrode22B also may store some of its energy/charge at or near its surface.

Those skilled in the art can select any of a variety of materials forthe shared electrode 22C. Some embodiments may form the shared electrode22C from a material better suited for a super-capacitor application. Forexample, the shared electrode 22C may act as an anode formed fromgraphene. In that case, illustrative embodiments may form the sharedelectrode 22C to have about the same capacitance as that of thesuper-capacitor electrode 22A.

Other embodiments, however, may form the shared electrode 22C from amaterial better suited for a battery application. For example, theshared electrode 22C may act as a cathode formed from lithium cobaltoxide (LiCoO2). In the latter case, the super-capacitor electrode 22Aand shared electrode 22C may be considered to form an asymmetricsuper-capacitor (suggested above). Accordingly, the shared electrode 22Cmay have both surface energy storage capacity and volumetric energystorage capacity, or surface energy storage capacity only. Indeed, asnoted above, those skilled in the art can select an appropriate materialfor the shared electrode 22C and thus, the materials discussed above arementioned for illustrative purposes only.

The electrolyte 24 can be formed from any of a wide variety of othercorresponding materials typically used in powering applications. Forexample, electrolyte 24 can be formed from an aqueous salt, such assodium chloride, or a gel, such as a polyvinyl alcohol polymer soaked ina salt. Additional examples include lithium tetrafluoroborate (LiBF4) orlithium hexafluorophosphate (LiPF6) plus polypyrole). Some embodimentsmay use an ionic liquid, in which ions are in the liquid state at roomtemperature. Although not necessarily aqueous, such electrolytes areknown to be extremely conductive due to the relatively free movement oftheir ions. The inventors believe that such an electrolyte 24 shouldcause the super-capacitor 26 to have a relatively high energy storagecapacity because, as known by those skilled in the art, the energystorage of a capacitor is a function of the square of the voltage.

As noted, the electrolyte 24 preferably is generally integrated withboth the internal and external surfaces of one or more of the electrodes22A-22C. Among other things, the internal surfaces may be formed bytortuous internal channels and pores within the electrodes 22A-22C. Theexternal surfaces simply may be those surfaces visible from theelectrode exteriors. The electrolyte 24 and noted electrode surfacesthus are considered to form an electrode/electrolyte interface thatstores energy.

Depending upon the electrode material, electrons can flow somewhatfreely within the electrodes 22-22C. For example, electrons can flowwithin graphene of the super-capacitor electrode 22A. The electrolyte24, however, acts as an insulator and thus, does not conduct theelectrons from the super-capacitor electrode 22A. In a correspondingmanner, the electrolyte 24 has ions that can migrate somewhat freely upto the noted interface with the super-capacitor electrodes 22A. Likeelectrons in the super-capacitor electrode 22A, ions in the electrolyte24 do not migrate through the interface.

Continuing with the super-capacitor electrode example, when subjected toan electric field, ions within the electrolyte 24 migrate to align withthe electric field. This causes electrons and holes in thesuper-capacitor electrode 22A to migrate in a corresponding manner,effectively storing charge. For example, in a prescribed electric field,positive ions in the electrolyte 24 may migrate toward a firstsuper-capacitor electrode surface, and the negative ions in theelectrolyte 24 may migrate toward a second super-capacitor electrodesurface. In that case, the positive ions near the first super-capacitorelectrode surface attract electrons (in the electrode 22A) toward thatinterface, while the negative ions near the second super-capacitorelectrode surface attract holes (in the electrode 22A) for thatinterface. The distance of the ions to the interface plus the distanceof the electrons to the same interface (on the opposite side of theinterface) represent distance “d” of Equation 1 above.

As noted above, the battery electrode and the super-capacitor electrode22B and 22A preferably are fixed at the same potential. Accordingly, asparallel-connected devices, the shared energy device 12 (i.e., thesuper-capacitor 26 and battery 28) effectively may meet both short-termpower spike/surge needs and long-term power needs. Other embodiments,however, may include switching circuitry to selectively connect anddisconnect the battery 28 and/or super-capacitor 26 from an underlyingcircuit.

To those ends, FIG. 3 schematically shows a diagram of the electricalconnections of the battery 28 and super-capacitor 26 within theintegrated circuit 10 of FIG. 1—a power circuit 37. More specifically,the power circuit 37 has circuit interfaces 32 that together receivepower from the combined shared energy device 12. Other circuits thus mayconnect to the two interfaces 32 for receiving the power. The powercircuit 37 also has one or more switches 34, along with a switchcontroller 36, for selectively connecting the battery 28 and thesuper-capacitor 26 between four different states. Those four statesinclude:

1) Parallel State: both the battery 28 and super-capacitor 26 are in thepower circuit 37—both switches 34 are closed,

2) Battery State: only the battery 28 is in the power circuit 37—onlythe switch 34 for the battery 28 is closed,

3) Super-capacitor state: only the super-capacitor 26 is the powercircuit 37—only the switch 34 for the super-capacitor 26 is closed, and

4) Disconnected State: neither the battery 28 nor the super-capacitor 26is in the power circuit 37—both switches 34 are open.

The switch controller 36 may control the switches 34 for any of a widevariety of power management functions. Among other ways, the switchcontroller 36 can receive switch control input from other circuitcomponents, or have preprogrammed instructions to make the appropriateswitching connections in the power circuit 37. The switch controller 36thus can be formed from a wide variety of conventional switchingdesigns, such as those using passive or active circuitry.

As noted above, the stacked electrode configuration of FIG. 2 is but oneof a wide variety of potentially viable electrode configurations for theshared energy device 12. FIGS. 4A and 4B schematically show theelectrode arrangements of two related but different embodiments havingoverlapping shapes. This overlapping is often referred to in the art as“interdigitating,” in a manner similar to the interlacing one's fingers.More specifically, the battery and super-capacitor electrodes 22B and22A in FIGS. 4A and 4B are formed in the noted overlapping configurationwithin same plane of the integrated circuit 10.

In the embodiment of FIG. 4A, the battery electrode 22B is a single,unitary electrode. In a similar manner, the super-capacitor electrode22A of FIG. 4A also has a single, unitary electrode. This is in contrastto the embodiment of FIG. 4B, in which the battery electrode 22B isformed by three separate and physically unconnected battery electrodes22B (they may be electrically connected). In a corresponding manner, thesuper-capacitor electrode 22A of FIG. 4B also is formed by threeseparate and physically unconnected super-capacitor electrodes 22A. Likethe separate electrodes forming the battery electrode 22B, theelectrodes of the super-capacitor electrode 22A may be electricallyconnected. For convenience, each of these electrodes 22A and 22B isreferred to as a “finger.” FIG. 4C schematically shows a cross-sectionof the electrodes 22A-22C across a plane that is substantiallyperpendicular to the plane of the substrate 14.

The embodiment of FIG. 4B thus permits power management circuitry (notshown) to selectively connect the various fingers as needed. Forexample, during system startup, to quickly boost system voltage fromzero to usable level for a given application, controlling circuitry maycharge and connect only a few super-capacitor fingers to the system. Asthe voltage increases, controlling circuitry may gradually charge andintroduce more super-capacitor fingers to the system. After thesuper-capacitor 26 fully charges and provides the initial power, thebattery 28 may act as the primary power source. Moreover, if the batteryand/or super-capacitor fingers has a defect or otherwise malfunctions,then controlling circuitry may remove that finger from the system. Whilethis solution may reduce power delivery capacity, it still may provideenough power for the given application.

FIGS. 5A and 5B schematically show another electrode configuration inwhich the super-capacitor electrode 22A and the battery electrode 22Balso are formed in the same plane of the integrated circuit 10. In thiscase, the super-capacitor electrode 22A circumscribes the batteryelectrode 22B, while the shared electrode 22C is formed in a differentlayer/plane of the integrated circuit 10. Indeed, this embodimentalternatively can circumscribe the battery electrode 22B about thesuper-capacitor electrode 22A, or circumscribe one of the battery orsuper-capacitor electrodes 22B or 22A about the shared electrode 22C. Inthe latter case, the other electrode 22A or 22B is in another plane. Itshould be noted that discussion of the specific electrodeconfigurations, such as those in FIGS. 2, 4A-4C and 5A-5B, are but a fewof a wide variety of different electrode configurations that may proveeffective. Accordingly, those skilled in the art can apply principles ofillustrative embodiments to form different electrode configurations thatincorporate the spirit of those embodiments.

FIG. 6 shows a process of fabricating the integrated circuit 10 inaccordance with illustrative embodiments of the invention. In thisexample, the integrated circuit 10 has an electrode configuration likethat of FIGS. 5A and 5B. It should be noted that this process issubstantially simplified from a longer process that normally would beused to form the integrated circuit 10 and its shared energy device 12.Accordingly, the process of forming the integrated circuit 10 has manysteps, such as adding the noted current collector layers 30, testing theindividual dice, or additional passivation steps that those skilled inthe art may use. In addition, some of the steps may be performed in adifferent order than that shown, or at the same time. Those skilled inthe art therefore can modify the process as appropriate.

It also should be noted that the process of FIG. 6 is a bulk process,which forms a plurality of integrated circuits 10 on the same wafer/baseat the same time. Although typically less efficient, those skilled inthe art can apply these principles to a process that forms only oneintegrated circuit 10.

The process begins at step 600, which deposits and patterns the batteryelectrode 22B on the insulated wafer/substrate 14. For simplicity, thewafer/substrate 14 is not shown in FIGS. 7A-7E. Among other ways, thisstep may use conventional sputtering or other well-known depositiontechniques, as well as conventional patterning techniques, to depositand pattern the battery electrode 22B. FIG. 7A schematically showsrelevant portions of the integrated circuit 10 at the conclusion of thisstep.

Next, the process coats the battery electrode 22B with a maskingmaterial 38, such as photoresist (step 602). Once the masking material38 cures, step 602 also patterns the masking material 38 into thenegative of the intended shape of the super-capacitor electrode 22A.FIG. 7B schematically shows relevant portions of the integrated circuit10 at the conclusion of this step.

Step 604 then deposits the super-capacitor electrode material onto themasking material 38, and then removes the mask, leaving the twoelectrodes 22A and 22B in place on the substrate 14. Accordingly, inthis embodiment, both electrodes 22A and 22B form anodes of theirrespective devices and are positioned on the same layer of theintegrated circuit 10. FIG. 7C schematically shows the relevant portionsof the integrated circuit 10 at the conclusion of this step.

The process continues to step 606, which deposits the electrolyte 24over both electrodes 22A and 22B. To that end, illustrative embodimentsmay pour or otherwise deposit a liquid electrolyte onto the exposed topsurface, and then apply a vacuum infiltration process to the substrate14, including to the electrodes 22A and 22B, which draws the liquidelectrolyte 24 into the porous electrode material forming the electrodes22A and 22B.

Illustrative vacuum infiltration processes preferably substantiallyuniformly distribute the electrolyte 24 within the porous materialwithout damaging the morphology of the electrodes 22A and 22B. Since theelectrolyte 24 is in liquid form, heating is not generally necessary atthis stage. Some embodiments, however, may omit the vacuum infiltrationprocesses. The step may conclude by permitting the electrolyte 24 tocure.

Rather than using a liquid electrolyte 24, some embodiments spin coat orotherwise deposit a solid/gel electrolyte to the substrate 14. Otherembodiments may use other electrolytes. FIG. 7D schematically shows therelevant portions of the integrated circuit 10 at the conclusion of thisstep.

At this point the process, the solid/gel electrolyte 24 is capable ofsupporting the shared electrode 22C. Accordingly, using conventionaltechniques such as sputtering, step 608 deposits the shared electrode22C onto the surface of the solid electrolyte 24. In this case, theshared electrode 22C acts as a cathode for both the super-capacitor 26and the battery 28. This step also may pattern the shared electrode 22Cif necessary. FIG. 7E schematically shows the relevant portions of theintegrated circuit 10 at the conclusion of this step.

After capping (e.g., using the cap 16) or otherwise encapsulating theintegrated circuit 10 (e.g., using an in-situ cap), the processconcludes at step 610, which separates/singulates the noted integratedcircuit dice formed on the substrate 14. Indeed, those skilled in theart can use any of a wide variety of techniques for separating the dice,such as conventional saw or dicing processes along scribe streets orprescribed regions. Other embodiments can use a perforated wafer, orother techniques known in the art. Regardless of the technique, thisfinal step of the process concludes with a plurality of die-levelintegrated circuit 10 having shared energy devices 12 ready for testing,further processing, or commercial use.

These resulting dice/integrated circuits 10 deliver a number ofbenefits. For example, as noted above, repeated power spikes can damagethe battery 28 under normal operating conditions. Illustrativeembodiments can mitigate that battery damage on a micro-chip level byhaving the super-capacitor 26 respond to spikes—effectively removing thebattery 28 from the circuit for the short duration of the spike. Thebattery 28 thus likely will provide the majority of the power to thecircuit in the steady state, while the capacitor primarily handles thepower spikes.

Illustrative embodiments therefore can deliver both high energy densityand high power functionality on a single, robust integrated circuit 10.By sharing the electrode 22C, such embodiments further can provide bothfunctionalities with a smaller footprint—using less die real estate.This should increase cost effectiveness and permit more devices to beformed on a single substrate 14. In addition, the shared electrode 22Creduces the necessary interconnections between the super-capacitor 26and the battery 28, correspondingly reducing internal die resistances,favorably reducing internal die power consumption.

Illustrative embodiments therefore provide the combined functionality ofthe super-capacitor 26 and battery 28 on the micro-level semiconductorscale; namely on a monolithic integrated circuit 10. This new designconsequently opens up a wide variety of new applications, enhancingcircuit design flexibility and functionality.

Although the above discussion discloses various exemplary embodiments ofthe invention, it should be apparent that those skilled in the art canmake various modifications that will achieve some of the advantages ofthe invention without departing from the true scope of the invention.

What is claimed is:
 1. An integrated circuit comprising: a substrate; asuper-capacitor supported by the substrate, the super-capacitorcomprising a super-capacitor electrode and a shared electrode; and abattery supported by the substrate, the battery comprising a batteryelectrode and the shared electrode, the super-capacitor and batteryforming at least a part of a monolithic integrated circuit.
 2. Theintegrated circuit as defined by claim 1 wherein the battery andsuper-capacitor are electrically connected in parallel.
 3. Theintegrated circuit as defined by claim 1 wherein the shared electrode isformed at least in part from a material so that it has surface energystorage capability and substantially no volumetric storage capability,the shared electrode comprising a shared anode for both thesuper-capacitor and the battery.
 4. The integrated circuit as defined byclaim 3 wherein the super-capacitor electrode and shared electrode haveabout the same capacitance.
 5. The integrated circuit as defined byclaim 1 wherein the shared electrode comprises a material having bothsurface energy storage capability and volumetric energy storagecapability, the super-capacitor forming an asymmetric super-capacitor,the shared electrode forming a shared cathode for the super-capacitorand the battery.
 6. The integrated circuit as defined by claim 1 furthercomprising at least one of active circuitry and MEMS structure supportedby the substrate and in electrical communication with the battery andthe super-capacitor.
 7. The integrated circuit as defined by claim 1wherein the integrated circuit comprises a plurality of layers, at leastone of the layers including two of the electrodes.
 8. The integratedcircuit as defined by claim 1 further comprising switching circuitry toswitch between at least a) a first state using the battery only, and b)a second state using the super-capacitor only, and c) a third stateconnecting the super-capacitor and battery.
 9. The integrated circuit asdefined by claim 1 wherein the super-capacitor electrode has a portionthat is interdigitated with a portion of the battery electrode.
 10. Theintegrated circuit as defined by claim 1 wherein the super-capacitorelectrode comprises graphene and the battery electrode comprisesgraphite.
 11. A micro-level energy storage device comprising: asubstrate; a first electrode formed from a material having surfaceenergy storage capability and substantially no volumetric energy storagecapability; a second electrode formed from a material having volumetricenergy storage capability; a third electrode formed from a materialhaving one or both surface energy storage capability and volumetricenergy storage capability; electrolyte in communication with the firstelectrode, the second electrode, and the third electrode; the firstelectrode configured to interact with the third electrode to form afirst energy storage device, the second electrode configured to interactwith the third electrode to form a second energy storage device, thesubstrate, first electrode, second electrode, and third electrodeforming at least a part of a monolithic integrated circuit.
 12. Themicro-level energy storage device as defined by claim 11 wherein thefirst energy storage device comprises a super-capacitor.
 13. Themicro-level energy storage device as defined by claim 11 wherein thesecond energy storage device comprises a battery.
 14. The micro-levelenergy storage device as defined by claim 11 wherein the first energystorage device is electrically connected in parallel with the secondenergy storage device.
 15. The micro-level energy storage device asdefined by claim 11 wherein the third electrode is configured to form ananode with both the first energy storage device and the second energystorage device.
 16. A method of forming an integrated circuit having anenergy storage device, the method comprising: forming a first electrodeon a substrate; forming a second electrode on the substrate; adding anelectrolyte to the substrate, the electrolyte at least partlyencapsulating the first and second electrodes; forming a third electrodeon the substrate, the third electrode being spaced from the first andsecond electrodes, the electrolyte being between the first electrode andthe third electrode, the electrolyte being between the second electrodeand the third electrode; separating the substrate into a plurality ofindividual monolithic integrated circuit dice, a plurality of the dicehaving the first electrode, the second electrode, and the thirdelectrode, the plurality of dice each being configured so that the firstelectrode interacts with the third electrode to form first energystorage device, each of the plurality of dice also being configured sothat the second electrode interacts with the third electrode to form asecond energy storage device.
 17. The method as defined by claim 16wherein the first energy storage device comprises a super-capacitor andthe second energy storage device comprises a battery.
 18. The method asdefined by claim 17 wherein the super-capacitor is electricallyconnected in parallel with the battery.
 19. The method as defined byclaim 16 wherein the electrolyte comprises a solid electrolyte material.20. The method as defined by claim 16 wherein the third electrodecomprises a material having one or both surface energy storagecapability and volumetric energy storage capability.